The present invention relates to intravascular repair methods and devices for treating hollow spaces such as aneurysms, fistulas, and other cavities and lumens within a patient's body, and is particularly suited for the treatment of intra-cerebral aneurysms of the cerebral vasculature.
The use of intravascular devices for the treatment of aneurysms has received an increasing amount of attention in the past several years as both the methods and devices available for intravascular procedures have become more efficacious. One such method involves the insertion of a foreign body, such as an occlusion coil, within the aneurysm to precipitate the formation of a clot or thrombus to thereby partially or completely occlude the aneurysm and seal off the aneurysm. This method typically poses the risk of the coil or ensuing thrombus migrating from the aneurysm to the parent artery and causing an undesired blockage. This method is also often limited to the treatment of aneurysms with small necks opening into the artery in order to ensure that the foreign body will remain within the aneurysm.
In another approach, a plug is inserted into the neck of a saccular aneurysm to block off blood flow into the aneurysm. If the plug is not sized correctly it may dislodge from the aneurysm and into the patient's vasculature. In addition, placement of such a plug necessitates robust contact with the aneurysm, which can cause rupture of the aneurysm and hemorrhaging.
Attempts have also been made to treat both saccular and fusiform aneurysms by deploying grafts within the vasculature and anchoring them on either side of the aneurysm. These grafts typically extend along the entire length of a fusiform aneurysm, or lie across the mouth of a saccular aneurysm, thereby completely blocking off the flow of blood to the aneurysm and relieving the pressure thereon.
Such graft devices may consist of a tube adapted to be disposed across an aneurysm and having a wire woven into one end of the graft that can be expanded to sealingly engage the vessel wall. The tube is preferably made of a suitable polyester material. In yet another approach to the problem, a sheet of resiliently flexible biocompatible material may be employed. The sheet is rolled upon itself about one of its longitudinal edges and is introduced adjacent to the aneurysm through a catheter to be expelled and expanded to form a bridge isolating the aneurysm from the flow of blood.
Certain other prior art devices contemplate the use of both a graft or stent and foreign bodies, the combination of which are used to repair an aneurysm. In such a system, the foreign bodies are placed within the aneurysm sac and the graft or stent is employed to retain the foreign material within the sac as well as to provide a passage for fluid flow. Due to the complexity of such systems, it is necessary to coordinate the sequence of deployment of the subcomponents of the system. To wit, the foreign bodies must be placed within the aneurysm sac prior to the placement of the graft or stent. Alternatively, in the event the graft or stent is first implaced at the repair site, the graft or stent must be provided with sidewall apertures or spaces through which the foreign material can be advanced to thereafter be placed within the aneurysm sac.
Although potentially successful in such applications as abdominal aortic aneurysms, certain of the prior devices do present a few drawbacks, especially in applications such as intracranial aneurysms. Among the more notable of the difficulties presented is the need to load such devices within a very small delivery catheter lumen and advance the same through typically tortuous pathways. In addition, the longer the graft emplaced at the repair site the larger the surface area for clot formation and endothelial cell growth, which in extreme situations can cause new complications for the patient. Also, such devices do not embody the ability to be deployed, detached and/or retrieved as would be necessary in the intra-cranial vessels. The risks posed by these devices increase in magnitude when the end organ is the brain, with its smaller vessel diameters, weaker vessel walls, and increasingly tortuous paths. The devices described above are thus less than ideally suited to intracranial intravascular intervention.
Moreover, any device placed in the parent artery of an intracranial aneurysm runs the risk of occluding perforating side branches. These perforators are small, usually less than 200 microns in diameter, and can be the sole source of blood flow to important tissues of the brain. Presently known devices such as vascular grafts and stents may partially or completely block the flow of blood to one or more such perforators, thereby causing clinically significant ischemic strokes.
Accordingly, what has been needed is a device for treating hollow spaces that has applications within narrow and highly tortuous vasculature characterized by having numerous perforators. The device should embody structure that not only creates a strong framework across an opening to the target space, but also should provide effective coverage of the opening. The present invention satisfies these needs.